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How to Stop Tissue Necrosis on your SPS

A common problem with SPS, especially Acropora, is Tissue Necrosis, which is essentially when the flesh begins to peel away from the skeleton. It is impossible for the coral to recover from areas where Tissue Necrosis has occurred. Generally speaking there are two types of Tissue Necrosis:

Rapid Tissue Necrosis (RTN)
Slow Tissue Necrosis (STN)

RTN typically happens abruptly and without warning and will consume the entire coral with 24 hours. STN begins slow and can continue as slow as 1mm a week. Without intervention of some sort, Tissue Necrosis will eventually kill the entire coral.

RTN is generally due to shock, either from parameters, temperature, etc. It occurs most often with new coral fragments entering our aquariums. It also occurs most frequently with "wild" acropora corals which have not acclimated to the aquarium environment. In my experience, STN is caused by too high or too low temperature and too high or too low salinity. STN and RTN can both by caused by acropora pests, such as AEFW, Red Bugs, Etc.

It is thought that Tissue Necrosis is caused by some sort of allergic reaction in the coral.

The first course of action when you see Tissue Necrosis is to determine if one of your parameters is out of balance, such a temperature, salinity, alkalinity, calcium, nitrates, phosphate, etc. Correcting this problem will prevent your other corals from falling to a similar fate.

The next step is to either fragment or super glue over the afflicted area. By super gluing or fragging past where the RTN or STN is occurring it will in some cases save the coral from further Necrosis. This process is similar to the technique of pre-burning strips of vegetation in a forest to stop the spread of forest fires.

Next time the flesh on your SPS begin to peel away take action, fragment the coral or super glue just past the farthest point of Necrosis.

Some people suggest dipping corals that are experience RTN or STN but generally speaking, the use of super glue or fragmentation is much more effective. You must "seal up" the peeling edge. Much like your own flesh after a bad sun-burn, it will just keep peeling away.

1. Superglue well above the Necrosis area - This works well for localized events and when there is STN. In cases that are tankwide events this method may not be feasible. In addition, in the cases of RTN, gluesuper only works if you catch it in the very early stages.
2. Reduce Lighting Intensity - This needs to be considered in the tool-kit to battle Necrosis. If corals are getting too much light, they cannot repair their tissue. This weakness could cause RTN or STN.

3. Increase Feedings or Nutrients - I believe it is far more likely that corals in starved aquariums are more likely to experience Necrosis. Acropora in higher nutrients typically just brown out. Increase feeding if your corals in general are pale and experiencing Necrosis.

4. Double Check Parameters, in Particular, Alkalinity - Low Alkalinity it probably the number 1 cause of Necrosis. Find the nicest and most successful aquarium in your area and grab a water sample and match their parameters with your test kits.

5. Ensure you don't have leaking voltage - Leaking voltage may be the cause of RTN and STN but this is highly debatable. Obviously removing voltage from the aquarium solving a safety concern, so you can't exactly argue against this solution, even if there is no link.

6. Inspect for Coral Eating Critters - I believe that astrenia starfish were rubbing on the edges/bases of my SPS causing STN. Remove these animals from your aquarium if you're experiencing Necrosis.

7. Nail your Salinity down - Again, find a tank in your area that has had long term success and match their salinity with your instruments.